Microstructure of Copolymers Formed by the Reagentless, Mechanochemical Remodeling of Homopolymers via Pulsed Ultrasound.

The high shear forces generated during the pulsed ultrasound of dilute polymer solutions lead to large tensile forces that are focused near the center of the polymer chain, but quantitative experimental evidence regarding the force distribution is rare. Here, pulsed ultrasound of quantitatively -dihalocyclopropanated (DHC) polybutadiene provides insights into the distribution. Pulsed ultrasound leads to the mechanochemical ring-opening of the DHC mechanophore to a 2,3-dihaloalkene.

Gemini surfactant electrospun membranes.

Our research demonstrates electrospun nonwoven fibrous scaffolds from a low molar mass gemini ammonium surfactant, N,N'-didodecyl-N,N,N',N'-tetramethyl-N,N'-ethanediyldiammonium dibromide (12-2-12). Cryogenic transmission electron microscopy (cryo-TEM) and solution rheological experiments revealed micellar morphological transitions of 12-2-12 in water and water:methanol (1:1 vol). The microstructure of 12-2-12 in water transitioned from entangled, cylindrical, threadlike micelles to branched threadlike micelles, and a viscoelastic, entangled, highly branched network of threadlike micelles with increasing concentration finally formed.

Biomimetic design and performance of polymerizable lipids.

Bilayer lipid membranes (BLMs) have received significant attention over the past several decades because of their applications in biological and material sciences. BLMs consist of two amphiphilic lipid layers arranged with their hydrophilic head region exposed to the surrounding aqueous environment and hydrophobic domains in the core. In biology, lipid membranes confine and support the cell structure while selectively controlling the diffusion of ions and proteins between the intra- and extracellular matrix (ECM).

Phospholipid nonwoven electrospun membranes.

Nonwoven fibrous membranes were formed from electrospinning lecithin solutions in a single processing step. As the concentration of lecithin increased, the micellar morphology evolved from spherical to cylindrical, and at higher concentrations the cylindrical micelles overlapped and entangled in a fashion similar to polymers in semi-dilute or concentrated solutions. At concentrations above the onset of entanglements of the wormlike micelles, electrospun fibers were fabricated with diameters on the order of 1 to 5 micrometers.